The evaluation of the transversal grip—also called transversal potential—of a tire on the snow is still carried out mostly subjectively, by means of a behavior survey performed by a professional driver.
While merely satisfying, this situation may be easily explained by the difficulties that have to be solved in order to carry out such a survey objectively.
In fact, in the case of rigid grounds, the transversal potential of a tire is usually evaluated by a driving test on a ring-like lane, of a predefined diameter, during which test the time period taken by a vehicle to perform a lap at the transversal grip limit is picked up. Nevertheless, this technique, in which the vehicle follows the same trajectory at each passage, leads, in the case of snow-covered grounds, to large errors due to the rapid changes of the running surface caused by the repetitive passage of the tires on the same tracks.